CONTACT CHEMORECEPTION IN THE TARNISHED PLANT BUG LYGUS LINEOLARIS

Abstract

The rostral tip of the tarnished plant bug contains two sensory fields each containing eleven sensilla basiconica. Removal of the rostral tip or antennae abolishes a feeding preference for frego bract cotton squares, suggesting that receptors at these loci are essential for a normal behavioral choice. Electrical recordings from the rostral nerve show increased impulse activity to stimulation of the rostral tip sensilla with juice from frego bract and normal bract squares of three varieties of cotton, confirming their function as contact chemoreceptors. Histograms of impulse frequency against time exhibit differences among the three cotton varieties tested.Although more than 70 species of Heteroptera are known to bear sensilla on the apex of the rostrum, there is no unanimity in the literature concerning their functioning (Cobben, 1978). Contact of the labial tip with the substrate is one of the first behavioral events of host recognition in Oncopeltus faseiatus and seems to provide information important for further feeding (Beck et al., 1958;Feir & Beck, 1963; Bongers, 1969). Although Frings & Frings (1949)concluded that there were contact chemoreceptors at the labial tip, since stimulation of these with sucrose resulted in ingestion of the solution, it was later pointed out by Miles (1958) that it was also possible for a test ingestion to occur, resulting in fluid contact with epipharyngeal chemoreceptors which in turn resulted in ingestion.The rostral sensilla in Dysdercusfulfonige'r and Dysdercus koenigii were shown by Schoonhoven and Henstra (1972) to consist of 24 sensilla basi,conica and two sensilla trichodea arranged in two sensory fields. Ultrastructurally the sensilla basiconica of these species and of D.fasciatus (Peregrine, 1972a) resembled contact chemoreceptors and preliminary electrophysiological studies by Schoonhoven and Henstra (t972) also supported a chemosensory role. Hansen et al. (1976) cite data of Bresch (1973) showing electrophysiological responses of the labial hairs of the cotton stainer Dysdercus to a wide variety of sugars.Behavioral observations of Dysdereus and Oncopeltus reveal that while the labial tip is being tapped against the substrate, a watery saliva is often discharged and sucked back through the stylets (Miles, 1958; Saxena, 1963). Thus, during the contact of the labial tip with a plant surface, both rostral and epipharyngeal

Morphology and distribution of the external labial sensilla in Fulgoromorpha (Insecta: Hemiptera)

“…Similar sensilla are known in other hemipteran taxa such as Aleyrodidae (Walker and Gordh 1989) or Heteroptera (Schoonhoven and Henstra 1972; Peregrine 1972; Gaffal 1981), but sometimes also reported as absent (Avé et al 1978; Hatfield and Frazier 1980; Rani and Madhavendra 1995; Brożek and Chłond 2010). As such types of sensilla are reputed to have an olfactory function (Slifer 1970; Zacharuk 1980; Steinbrecht 1984; Hallberg et al 2003; Kristoffersen et al 2006; Onagbola and Fadamiro 2008), one can say that the Hemiptera labium assists the antenna in this function, but the association has not yet been fully studied.…”

“…In Heteroptera, the labial sensilla have been studied in more than 70 species (Beck et al 1958; Schoonhoven and Henstra 1972; Peregrine 1972; Cobben 1978; Avé et al 1978; Gaffal 1981; Backus 1988; Rani and Madhavendra 1995; Ventura et al 2000; Ventura and Panizzi 2005; Brożek 2008; Brożek and Chłond 2010). …”

“…Morphological evidence on the labial tip of other hemipterans suggested that contact-chemoreceptive sensilla occur rather frequently in Heteroptera (Schoonhoven and Henstra 1972; Avé et al 1978; Hatfield and Frazier 1980; Gaffal 1981; Rani and Madhavendra 1995; Rani 2009; Baker et al 2008) and Aleyrodidae (Walker and Gordh 1989) and Psyllidae (Garzo et al 2012). Conversely, sensilla basiconica (BSN1, BSN2) that are the second most abundant type of sensillum found on the tip of the labium in Fulgoromorpha are typical mechanoreceptive sensilla.…”

First predation record ofCanthecona furcellata(Wolff.) (Hemiptera: Pentatomidae) on spinning stage silkwormAntheraea mylitta(Drury)

“…The rostrum is in contact at the coxal base to the anterior abdomen and the wings are usually folded flat over the abdomen at rest, as also observed by Usha Rani (), with a similar arrangement in other hemipteran species as reported by earlier workers (Peregrine ; Avé et al . ; Cobben ; Gullan & Cranston ). SEM imaging of the proboscis reveals the presence of a labial tip, mandibular and maxillary stylets, similar to that reported in earlier observations (Usha Rani et al .…”

Comparative Analysis and Systematic Mapping of the Labial Sensilla in the Nepomorpha (Heteroptera: Insecta)

“…In gerromorphan bugs a richer and more diverse sensory equipment (several morphological types of sensilla) has been detected [Brożek and Zettel, in prep]. An undifferentiated sensory system occurs in the Pentatomomorpha (e.g., Dysdercus fulvoniger and D. koenigii , D. fasciatus, D. intermedius, Lygus lineolaris, and Neomegalotomus parvus ), where the labium tip usually represents one morphological type of basiconic sensilla functioning as the contact-chemoreceptive sensilla (several pairs), basiconic gustative sensilla (several pairs), and basiconic olfactive sensilla (one or two pairs) [17, 19, 21, 22, 37]. In some of the Reduviidae one type of peg and peg-in-pit sensilla have been noticed [15, 25, 38].…”